Circuit interrupter



Aug. 21, 1934. wALLE CIRCUIT INTERRUPTER Filed Dec. 1, 1932 Fig. I.

Inventor Luohx Q S.\X/alle,

by His Attorney Patented Aug. 21, 1934 UNITED STATES 1,971,205 omoorr INTERRUPTER Ludwig S. Walle, Lansdowne, Pa., assignor to General Electric Company, a corporation of New .York

Application December 1,

1932, Serial No. 645,257

8 Claims. (01. 200-88) My invention relates to circuit interrupters of the type arranged to be opened in response to different magnitudes of load current flowing through the contacts of the circuit interrupter,

and has for an object the provision of a simple, inexpensive and rugged device of this character.

Heretofore it has been suggested that circuitsmay be interrupted in response to the heating effect of the current in the circuit and in response to the magnetic flux produced by the flow of current. However, in such devices much is yet to be desired in securing this result by a device having a minimum number of moving parts and which is readily applicable to high speed circuit breakers.

In carrying out my invention in one form thereof I arrange a U-shaped bimetallic latch responsive to current flow and to the magnetic field produced by the current, so that the circuit breaker is released by the latch in accordance with a predetermined heating of the bimetallic latch or with a predetermined magnetic attraction produced by the magnetic field.

For a more complete understanding of my invention reference should now be had to the drawing in which I have shown diagrammatically in Fig. 1 a circuit breaker embodying my invention, while in Fig. 2 the circuit breaker of Fig. 1 is shown in exploded perspective.

Referring to the drawing, I have shown my in-' vention in one form as applied to the operation of a circuit breaker 10 mounted upon a panel 11. A fixed contact 12 is secured to the panel while a cooperating movable contact 13 is supported by a link 14 which forms a part of a toggle mechanism 16. The link 14 is mounted for pivotal movement about the pin 18. The lower end 19 of the link 14 is pivotally connected by the pin 20 to a link 21 which is pivoted at its lower end by a pin 22. An operating handle 23 is rigidly secured to the link 21 so that the movable contact 13 maybe operated either to anopen or a closed position.

Toggle mechanisms of this general type are well known to the art and. it is to be understood that my invention may be applied to any type of 5 circuit breaker which is normally biased to one position and which is restrained in another position by a toggle or other equivalent mechanism. As shown, the toggle is arranged to be broken by the downward movement of a tripping lever 24.

0 This lever, pivoted at one end to the pin 22, is

provided with an upwardly projecting arm 25 arranged to be moved into engagement with the lever 21 to break the toggle. The tripping lever 24 is biased for rotation around the pivot 22 as by means of a weight 27. The end 28 of the tripping lever 24, as shown in the drawing, rests upon a plate 29 secured to the U-shaped bimetallic element 31. This bimetallic thermal element 31 forms a part of the circuit which includes the contacts 12 and 13. This circuit may be traced by conductor 32, stationary contact 12, movable contact 13, flexible conductor 33, connecting block 34, U-shaped element 31 and to conductor 36. Adjacent the panel 11 and spaced 9. short distance from the thermal element 31 there is mounted a plate 38 of magnetic material. Cooperating with this plate there are arranged the plates 39 and 40 of magnetic material respectively associated with the legs of the thermal element. The plate 39 is pivotally supported at its upper end on a bushing 42 carried by a bolt 43. The bushing 42 is forced against the thermal element by the nut 44 to insure a good electrical connection between the element and the conductor 36. To prevent lateral movement, the upper end of the plate 39 is channel-shaped. Opposite the magnetic plate 38, there are arranged extensions 45 on the plate 39. The distance betw'eenthe ends of the flux concentrating extensions 45 and the plate 38 isgreat enough so that the thermal element 31 may be so moved by the plates 39 and 40 to open the circuit breaker. It will also be seen that the ends of the extensions 45 adjacent the plate 38 are angularly disposed with respect to the plate 38 so that relatively short flux paths are formed at the upper 35 portions of the extensions. Furthermore, as the plates 39 and 40 are pivotally swung about their supports the relatively large air gaps at the lower ends of the extensions are rapidly decreased. The plate 40 is identical in construction and operation with the plate 39.

In the operation of my invention in the form shown the circuit breaker 10 is arranged to be opened upon the occurrence of a current flow of predetermined magnitude, which magnitude is maintained for a predetermined time. Furthermore the circuit breaker will be quickly operated to the open position in case of a current flow of a greater predetermined magnitude. It will be remembered that the load circuit was traced by the conductor 32 through the contacts 12 and 13 and the bimetallic thermal element 31 which element is slotted to form a current path through it. A predetermined heating of the thermal element 31- incident to the flow of current produces a movement of the element 31 away from the end 28 of the tripping member 24. Consequently, if a current flow of a predetermined magnitude is sustained for a sufiicient length of time the movement of the element 31 releases the tripping arm 2 1 which operates to break the toggle mechanism 16. In case of an overload or a short circuit, a current of large magnitude will flow through the thermal element 31. As a result of a large how of current there is produced around each leg of the thermal element a strong magnetic field which causes the magnetization of the members 39 and 40 and the plate 38. An attractive effort is therefore produced between the movable plates 39 and 40 and the stationary plate 38. As soon as this effort becomes sumciently great the plates 39 and 40 are rotated about their pivots. The air gap between the movable plates 39 and 40 and the stationary plate 38 is quickly reduced and a relatively strong attractive effort is produced. The plates 39 and 40 thereupon move bodily the thermal element 31 away from the end 28 of the tripping lever 24. Under the influence of the weight 27 the tripping lever 24 is rotated in a counterclockwise direction so that the extension 25 strikes the link 21 to break the toggle and to operate the movable contact 13 to an open position.

In order to reclose the circuit breakers it is only necessary to return the handle to the position shown in Fig. 1 which, it will be observed, returns the tripping lever 24 to its latched-in position and at the same time operates the movable contact 13 to a closed position in engagement with the stationary contact 12.

It will, of course, be understood that additional contacts corresponding to the contacts 12 and 13 may be provided for additional circuits. For example, in a three phase system three pairs of contacts will be provided and in circuit with each phase there will be included a thermal responsive element 31. Preferably, the tripping lever 24 will be arranged to be released by operation of any one of the thermal elements.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a circuit breaker, the combination with a switch biased towards one position, releasable restraining means therefor, of a U-shaped bimetallic strip for operating said restraining means, mounting means connecting said strip in circuit with said circuit breaker and fixedly mounting said strip from its adjacent legs, a U- shaped magnetizable member for each leg of said strip pivotally supported from said mounting means and partially encircling a leg of said bi- 1r atallic strip, a stationary magnetizable member spaced apart from said U-shaped magnetizable members whereby said strip can be operated either thermally or by the movement of said U-shaped members against the legs of said bi metallic strip.

2. Ina circuit breaker, the combination with a switch biased towards one position, releasable restraining means therefor, of a U-shaped bimetallic strip for operating said restraining means, mounting means connecting said strip in circuit with said circuit breaker and fixedly supporting said strip from its adjacent legs, a U-shaped magnetizable member for each leg of said strip pivotally supported from said mounting means, each of said U-shaped magnetizable said leg, a stationary magnetizable member spaced apart from said U-shaped magnetizable members, said magnetizable members forming a gradually increasing air gap from top to bottom of said stationary magnetizable member to increase rapidly the attractive effort between said magnetizable members as relative movement of said members is initiated.

3. In combination, a current conducting bimetallic element movable from one position to another position in response to the heating effeet of current flow, and relatively movable magnetizable members disposed in the path of the flux surrounding the current conducting bimetallic element with an air gap therebetween which is normally greater at one portion than at other portions and which is substantially closed upon movement of the element by said members from said one position to said other position.

4. A latch for circuit breakers of the type having contacts normally biased to one position and operable to another position comprising a bimetallic strip connected in circuit with said contacts and responsive to the heating eifect of current flow for releasing said contacts, a stationary magnetizable member adjacent said strip, magnetizable members forming a partial path for the magnetic flux produced by said current arranged on opposite sides of said strip for movement so that the magnetic attraction between said members operates said movable members against said strip to release said contacts in response to a predetermined current flow.

5. In combination, a bimetallic thermal element slotted to form a current path through adjacent legs of said element, means fixedly mounting said element from the ends of said legs, magnetizable members arranged for movement against said legs of said element, a stationary magnetizable member supported in spaced relation with and on the opposite side of said element, said magnetizable member forming a gradually increasing air gap from top to bottom of said stationary member to increase rapidly the attractive effort between said magnetizable members as relative movement of said members is initiated.

6. A latch for a circuit breaker having contacts normally biased to an open position comprising a U-shaped bimetallic strip, means supporting said strip from its open end to hold said contacts closed, connections for connecting said strip in circuit with said contacts to cause the release of said contacts in response to the heating of said strip due to a predetermined current flow in said circuit, a stationary magnetizable member fixedly secured on one sideof said strip, and a movable magnetizable member arranged on each end of said strip and extending on the other side of said strip to a position opposite said stationary magnetizable member so as to operate said strip to release said contacts upon the occurrence of a predetermined current How in said circuit.

7. The combination with a circuit breaker having contacts normally biased to an open position and a toggle mechanism for holding said contacts closed, of tripping means for breaking said toggle to release said contacts, a latch movable from one position to another to release said tripping means, said latch including a U-shaped bimetallic element, connections for connecting said element in circuit with said contacts so as to produce heating of I memes said element by current flew therethmugfi, a

megnetizebie piste arranged in juxtepesitien te seiii eieiiieiit, aseeomi msgnetisabie mete means piveteily supporting said second; piste on the opposite side of said element, said eie= merit being free te move independently ei'f seseemed plate, projections formed an oppesite 0? said second piste anti partially extendins; is said. first plate, the said second plate ieeme free to meve against said element whereby eeiiteets can be opened by heating of eieiiieiit or by magnetic ettraetieii of said ele meet 8: In a circuitieresker, the combination with it switch biased towards one pcsitieii, reiessable restraining means thereieig of e Li -shaped bimetallic strip for releasing said restraining means, conductors for connecting said biiiieteiiie strip in series circuit relation with said circuitbreakers, fastening means fer rigidly seeming the less of seiei bimetallic strip te said coiii dueters, e u sheped imegiietizsbie member for each leg 0i said strip pivetaiiy supported from fastening means and arranged for mave meiit against its esseeieted. leg of said bimeteii lie strip, a stationary megiietizabie member spaced apart from Said U-s'i apeci megnetizsbie member, eeeii oi" sem U-shaped megnetizatiie members being formed to previiie a, gradusiiy increasing air gap from tsp t0 bettem of said stew tienem member te increase rapidly the ettree tive effort between said megnetizeble member as said U-sheped magnetizemie members are moved towards seici magnetizebie member whereby" the magnetic circuit between said meiw hers is substantially closed when seid U-shaped. members operate said strip te release seioi re= straining members LUDWTG VAL E 

